Some medical devices may monitor one or more hemodynamic characteristics of a patient, such as the blood oxygen saturation level in arterial blood, arterial pulses of the patient, and the like. Example medical devices that monitor hemodynamic characteristics of a patient include optical sensors, such as pulse oximeters. One type of optical sensor includes at least one light source that emits light through a portion of blood-perfused tissue of a patient, and a detector that senses the emitted light that passed through the blood-perfused tissue. An intensity of the light sensed by the detector may be indicative of hemodynamic function of the patient, such as oxygen saturation of blood of the patient.
In some types of optical sensors, one or more light sources may be positioned on the same side of the blood perfused tissue as the detector, such that the detector detects light emitted by the light sources and reflected by blood. This type of optical perfusion sensor may be referred to as a reflectance optical sensor. In other types of optical sensors, referred to as transmissive sensors, one or more light sources may generally oppose the detector, such that the detector senses light that is transmitted through the blood perfused tissue.